Flow Meters

Mike T., Swampeast MO

Anyone know of reasonably accurate flow meters suitable to low flow in a large pipe, i.e. 5 GPM through 1 1/4" black iron?

Harder still--not hideously expensive? Particularly since I need two for my application (before & after bypass). Data would be meaningless without both.

With both (and risking circulator damage by operating it off a dimmer) I could actually answer the question "how big a pump do you actually need in a gravity conversion?"

Am at a complete experimental loss without this info as I can't even calculate it in a "backward" fashion by measuring the head developed by the circulator. While my differential pressure bypass has a gauge that can do this, it has NEVER had a discernable indication--even with all of the TRVs closed. The gauge is crude and my method of setting even more crude--press my ear against the valve and adjust for a bit of flow at all times, then "tweak" the setting by trying to adjust for longest, least frequent firing time at warm outside temp. It is amazing (to me at least) how much you could change the firing frequency of the boiler with tiny adjustments at the bypass.

Wish I kept MUCH better notes in a PROPER place. I wind up with pages and pages of paper filled with numbers scattered in various bookshelves/bathrooms--and sometimes don't even write down what the numbers were to begin with! Bad--I know.

Had a viral disaster that wiped out a number of really good spreadsheets and I'm only left with hard-copy printouts. Didn't keep good backups of that computer and paid the price!

Tony Conner

You Could Try...

...rotameters. You likely already know what they are, but I'll run through it anyway. They're variable area flow meters that have to be installed in vertical lines with the flow going up. They have a clear, graduated tube that starts off smaller, and gets progressively larger. A small ball is moved by the flow. TIG welding rigs use them to allow the welder to set the flow of argon from the bottle to the torch cup. They ones I've seen are just for local use, I haven't seen them with outputs that could send a signal anywhere, except as an alarm for low flow conditions. As long as you don't mind standing at the meters to get your readings, your all set. If you need some sort of data logging function, I don't know if these would be what you're looking for.

Art Pittaway

B&G used to make

an inline flow measuring device. No electric, it was a spring loaded device that you piped in and could set the flow right with a screwdriver where you wanted it. I think they made them through 2 or 3 inch. Used two of them to set the flow on a couple of Burkay heaters that were chewing up cores. Worked perfect. Price and acuracy is how you define it.
Art

Dave H_2

Check these out

http://www.mcmaster.com/catalog/108/html/0444.html

These might help

Mike T., Swampeast MO

Don't want to set flow...

...just measure it AS IT CHANGES.

Mike T., Swampeast MO

Close but I couldn't leave them installed...

150° max? Even my system might get that high sometime. And the ones said to be "more durable" are only good to 130°

Glenn Harrison

How about Dwyer Instruments @ www.dwyer-inst.com
I know they have a variety of flow meters.

Steve Miller

Blue and White

I like the flow meters from Blue and White Industries and used them with good success. I think the one for you would be the F 451 model.

Steve

[Deleted User]

Try...

http://www.2hsc.com/pdfs/Page177.pdf

for Letro flow meters. In line, in stock and ready to plumb.

ME

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Dave_4

onicon makes turbine type

1 or 2% accuracy...reads down to 0.8 gpm....depends how you define hideous....

Duncan_2

Letro

Mike, back in the day, we used inline flow meters made by Letro for solar loops. They're simple and rugged, fairly inexpensive as flow meters go, and most importantly, they lasted in high temp loops. They need to be mounted vertically.

Unfortunately, they don't come in 1-1/4" size. But for a single point restriction in a piping system, it's not gonna add much head. They might meet your criteria.

They're good, I wouldn't do ya wrong. Experience talks.

http://www.cisolar.com/catSolhotparts.htm

Stay away from Cal-Q-flow, they don't take high temps well in my experience.

hr

www.blue-white.com

has been around for years. Clean fluid helps keep the window clear. Some guys use a dash of bright green glycol for easy readability. Lots of sizes and conection available.

hot rod

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